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June 19, 1956 P. H. ALLEN ET AL 2,751,148

LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS Filed Nov. 6, 1952 5 Sheets-Sheet 1 FIE-.1...

INVENTORS J1me 1956 P. H. ALLEN ET AL LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS 5 Sheets-Sheet 2 Filed Nov. 6. 1952 INVENTORS June 19, 1956 P. H. ALLEN ET AL 2,751,148

LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS Filed Nov. 6, 1952 5 Sheets-Sheet 3 Q INVENTORS June 19, 1956 P. H. ALLEN ETAL 2,751,148

LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS Filed Nov. 6. 1952 5 Sheets-Sheet 4 INVENTORS June 19, 1956 P. H. ALLEN ETAL 2,751,148

LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS Filed Nov. 6. 1952 5 Sheets-Sheet 5 F1E 1:5 3v

INVENTORS i/kzg.

United States Patent LIGHT RESPONSIVE CALCULATING MACHINE CONTROLS Philip H. Allen, Los Gatos, Calif., and Benjamin J. Chromy, Washington, D. C.

Application November 6, 1952, Serial No. 319,091

11 Claims. (Cl. 235-61) This invention relates to registers and similar devices such as calculating machines of the type employing optical-electrical control means for controlling machine operations, and is concerned more particularly with the provision of improved control means of the above character.

It is a general object of the invention to provide improved operation control means for registering apparatus.

Another object of the invention is to provide optical electrical control means in a registering device which employs a single light-responsive control circuit for selectively exercising control over a plurality of associated operation control means.

A further object of the invention is to provide optical control means for a registering device employing modulated light.

Still another object of the invention is to provide control means employing different electrical frequencies in a common circuit for pick-up by tuned electrical operation control means.

Other objects of the invention will be apparent from the following description of the preferred embodiment of the invention as illustrated in the accompanying drawings, in which:

Figure l is a plan view of a calculating machine embodying the instant invention.

Figure 2 is a sectional plan view of the optical-electrical control system of the machine.

Figure 3 is a view of the optical-electrical control means including a sectional portion taken as indicated by the line 3-3 in section 2 of the light source and the light modulating means, and also a schematic wiring diagram of the electrical portion of the control means.

Figure 4 is a sectional elevational view of a portion of the optical-electrical control means taken as indicated by the line 4-4 in Figure 2.

Figure 5 is a fragmentary enlarged view of a portion of Figure 4 illustrating certain details on construction.

Figure 6 is an enlarged elevational view of a portion of Figure 5 taken as indicated by the line 66 of Fig ure 5.

Figure 7 is a front sectional elevation of a portion of the optical-electrical control means taken as indicated by the line 77 in Figure 2.

Figure 8 is an elevational view of a portion of the optical control system taken as indicated by the line 88 in Figure 2.

Figure 9 is a fragmentary elevational view of a part of the optical control means taken as indicated by the line 9-9 in Figure 2.

Figure 10 is a sectional view illustrating the optical overdraft control employed in performing division operations.

Figure 11 is a fragmentary sectional view taken as indicated by the line 1111 in Figure 10.

Fig. 12 is a fragmentary sectional view illustrating one method of operating certain of the machine controls.

Figure 13 is a sectional view illustrating a method of operating the main clutch and circuit controls of the machine.

Generally the instant invention contemplates the use of light rays and light responsive devices for exercising the various-control functions of the machine such as engagement of the main clutch, the shift clutches, the resetting clutches and exercising the overdraft control in performing division. In general the invention has been shown as applied to the optical-electrical control means of the type disclosed in'our Patent No. 2,651,463. The invention may be applied to conventional forms of calculating machines such as are now on the market under the trade names of Marchant, Monroe, and Friden, and is illustrated in connection with a calculator of the character disclosed in the patent to Carl M. Friden No. 2,229,889 dated January 28, 1941, and patents of Carl M. Friden, No. 2,371,752, and Carl M. Friden and Anthony B. Machado, No. 2,399,917.

Referring to Figure 1 the calculator includes a body 25 in which the actuating, selecting and control mechanisms are mounted, and carriage 26 which is mounted for endwise shifting movement traversely of the body 25 and which carries numeral wheels 27 and 28 of the accumulator and revolution counter respectively. Carriage 26 can be shifted by power in either direction by manipulation of respective shift keys 29 and 30 through mechanism of conventional character.

Values are entered into the calculator by depression of numeral keys 32 of the usual value entering or mul tiplicand keyboard in various ordinal rows thereof, keys 32 being releasable individually by the depression of ordinal clear keys 320 or collectively by depression of clear key 33. Values introduced into the calculator may be registered additively or subtractively on numeral wheels 27 by depression of plus key 34 or minus key 35, respectively. If desired add key 36 may be depressed to cause'clearing of the keyboard in the usual manner after single registrations in the accumulator.

Values registered in numeral wheels 27 and 28 can be removed through resetting mechanism operated by manipulation of respective manually operable resetting handles 37 and 38 or by power through depression of return and clear key 39.

The calculator is adapted to perform automatic plural order division by means of conventional division mechanism including the starting control key 41 of the character disclosed in the patent of Carl M. Friden, 2,327,981, issued August 31, 1943. Automatic predetermined multiplication can also be performed by depression of the multiplier selection keys 42 to set up the desired multiplier figure as indicated on dials 43, and by depression of one of the multiplication keys 44, 45 or 46, to start the multiplying operation. Key 47 is a correction key for correcting the multiplier figure and zeroizing the indicating dials 43.

In exercising the optical-electrical control of the various machine functions there is provided a source of a plurality of light rays which provide a ray for each machine function to be controlled and whose path passes by the various control keys or elements controlled thereby so that the path of a light ray can be varied upon depression of control keys to cause impingement thereof on a light responsive device. The light responsive device is electrically connected to a solenoid which operates a mechanical control element of the calculator which must be moved to effect the desired machine function, as disclosed in our patent.

Referring to Figures 2, 3 and 4 there is illustrated a lower body portion 25a in the form of an auxiliary light-proof casing which is disposed below the conventional parts of the calculator, but in alignment with the general plane of the calculator. Within the body portion 25a there is provided an auxiliary housing 51 having a chamber 52 containing a rotary cylindrical shutter 51a inside of which is positioned a source of light 53 such as a neon or fluorescent tube. A second chamber 54 having a single elongated light responsive device or plurality of light responsive devices 55 which may be connected together and which may be of any desired type such as a resistance type selenium cell, a conduction type phototube, an electron emissive cathode tube, or a photovoltaic cell, is formed on the side of the housing 51. The housing 51 is provided with a series of vertically aligned pairs of apertures 56 through 60 respectively so that five collimated light rays are produced which are normally projected along a path indicated by the dot and dash lines 61 in Figure 2, and optical means are associated with the light rays to provide respective paths thereof disposed beneath the various operation control keys of the machine for the desired machine functions. This optical system includes a series of reflecting elements or mirrors 62 through 67 respectively. In the present embodiment all of these mirrors are disposed at an angle of 45 with respect to an impinging light ray so that the light ray is reflected at an angle of 90 to its former path in each instance, the arrangement of the mirrors being such that the light rays following the mirror system 62 through 67 will impinge upon an opaque wall portion of the housing 51 as indicated in Figure 2 out of alignment with a series of apertures 68 through 72 respectively (Figure 3) which lead to an associated light sensitive device 55 as previously described.

In order to exercise a controlling function with respect to the light rays each of the control keys is extended to have its lower end disposed above a flexible bellows 76 (Figures 4 and enclosing an aperture 77 in the body portion 25a and having the upper end of an auxiliary key stem 39a, for example, in abutting relation with the top surface of the bellows. The auxiliary key 39a is guided in the upper wall of the body portion 25a and in a suitable guide 78 in the bottom wall of this housing. A spring 79 serves to maintain the auxiliary stem 39a in elevated position.

While this auxiliary key stem construction has been described in connection with the resetting key 39 it will be understood that similar auxiliary keys are provided in connection with the control keys 29, 30, 34, 35, 41, 44, 45, 46 and 47 of the calculating machine and these auxiliary key stems or auxiliary control keys have been designated by like numerals with the addition of the suflix a. The auxiliary key 39a is provided with a light ray controlling optical system including a pair of parallel reflecting elements or mirrors 81 and 82 which are disposed immediately above the uppermost light ray emerging from the apertures 56. These mirrors 81 and 82 are at an angle of 45 with respect to the light ray so that when moved into the path of the light ray the effect is to laterally displace the associated light ray so that it impinges upon the reflecting mirror system 62 through 67 at a dilferent position and will pass through the corresponding aperture 68 to impinge upon the light sensitive device 55. This condition is indicated by the line of dashes in Figure 2.

From the above description it will be seen that whenever the control key 39 for example is depressed the mirrors 81-82 associated with the uppermost light ray employed for controlling the main clutch will cause a variation or displacement of the path of the light ray so that it will be placed in operative relation with respect to the light sensitive device 55. The auxiliary key 39a is provided with a second set of mirrors 83-84 which are disposed immediately above the light ray emerging from the apertures 59 and associated with the resetting control in a manner later described, this light ray entering the aperture 71 (Figure 3) when deflected by the mirrors 8384. The key 39a is also provided with a third set of mirrors 85-85a associated with the light ray emerging from the 4 apertures 57 associated with the shift mechanism as later described.

In the case of the main clutch control, that is the light ray provided by the upper most apertures 56, each of the control keys is provided with mirrors corresponding to the pair of mirrors 81--82 for causing engagement of the main clutch upon depression of any one of these keys. For this purpose the light sensitive device 55 is connected through an amplifier 86 (Figure 3) to a solenoid 87 so that the solenoid 87 will be energized as later described when any of the control keys are depressed. The solenoid 87 (Figure 13) has its armature 88 connected to a lever 89 to cause pivoting movement of the lever 89 when the solenoid is energized. The lever 89 is pivotally connected to a lever 90 forming a part of the conventional clutch control of the Friden type calculator as disclosed in the above patent and also forming a control for the circuit making contacts 91 of the electric drive motor. The clutch controlling mirrors of the remaining control keys are numbered similarly to the mirrors 81-82 but with the suffixes a, b, c, d, e, etc.

The mirrors 83-84 on the auxiliary resetting key 39a serve to deflect the fourth light ray emerging from the apertures 59 when in operative position and cause this ray to impinge through apertures 71 upon the light sensitive device 55 which is electrically connected also through amplifier 86 to the solenoid 93. The solenoid 93 is operatively connected to shift the resetting clutch control rod of the Friden calculator as illustrated in Figure 12. The armature of the solenoid 93 is connected to a pivoted lever 96 having a forked upper end embracing the conventional resetting clutch shift rod 97 of the Friden calculator and engaging a collar 98 thereon. The deflecting mirrors and 85a at the same time serve to deflect the light ray from the apertures 57 to cause it to pass through the apertures 69 and eflect operation of the left shift mechanism so that the carriage will be returned to its left end position as a preliminary to the resetting operation. The mirrors 85 and the mirrors 8le, 101 and 103 referred to hereinafter, are arranged in pairs the same as the mirrors 81 and 82 shown in Figure 6.

Thus, whenever the resetting control key 39 is operated both the main clutch, the resetting clutch and the left shift clutch are engaged to effect the resetting operation with respect to the accumulator and revolution counter as disclosed in the above named Friden patent. By virtue of the fact that the resetting control light ray traverses a path extending at various points along the operative controls of the calculator it is apparent that at any other selected point along this path or along another desired path a second resetting control key could be installed to function in the same manner as the key 39 and the auxiliary key 39a.

The auxiliary right and left shift keys 29a and 30a have respective sets of mirrors 101-102 and 103-404 associated respectively with the light rays from the apertures 58 and 57, respectively, so that these light rays upon depression of either shift key will be offset in the manner previously described to cause the light rays to enter either of the apertures 70 and 69 and operate the light sensitive device 55. The light sensitive device is connected through the amplifier 86 with respective solenoids 107 and 108 as will be presently described and these solenoids 107 and 108 are associated with the respective left and right shift control rods of the Friden calculator in the manner described in connection with the shift clutch control rod 97 illustrated in Figure 12. Thus upon depression of either shift key the associated shift clutch will be engaged as well as the main clutch jto effect shifting of the carriage in the desired direction. It is obvious that additional shift keys could be employed at other portions of the paths of the light means associated with the shift control mechanism and that automatic shifting in the course of division or multiplying perations may be performed by providing appropriate ight ray control mirrors such as those indicated at 118-119 in Figure 2.

Also, the respective auxiliary shift keys 29a and 30a are provided with respective shutters 110 to block olf, respectively, the control light ray for the other shift key, and thereby provide an interlock without the use of mechanical interconnection.

In order to perform automatic division operations with an optical electrical control a special main clutch control is provided as well as a normally disabled overdraft control as will now be described.

In order to prevent effective operation of the division key when the register carriage 26 is in its lowest ordinal position where only one significant quotient figure could be registered the mirror 62 is provided with a halfsilvered portion 62a (Figure 4) in alignment with the clutch control light ray from the apertures 56 so that a portion of this ray is reflected to follow the normal path along the mirrors 63 through 67 while the second portion is passed through the half-silvered mirror 62a and this second portion traverses a path leading past the control mirrors 81e--82e of the auxiliary division key 41a to a 45 mirror 111 (Figures 2 and 4). The ray reflected from the mirror 111 is offset upwardly by a pair of 45 parallel mirrors- 112-113 (Figure 7) so that the light ray passes through an aperture 114 in a supporting bracket for the mirror 64 and impinges upon the uppermost portion of the mirrors 65, 66, and 67 in a plane located above the housing 51. An additional deflecting mirror 116 is provided (Figure 3) to direct the ray downwardly through an aperture 117 to impinge upon the light sensitive device 55. Associated with this division clutch control light ray is a shutter 118 (Figure 4) which is depressed to its dotted line position by the register carriage 26 in any convenient manner when the carriage is in its leftmost position so that depression of the division key 41 is inoperative with the carriage in this position to initiate a division operation as the main clutch can not be engaged.

To provide an optical-electrical overdraft control the lowermost light ray from the aperture 60 (Figure 4) passes immediately beneath a single reflecting mirror 121 carried by the auxiliary division key 41a and when the division key is not depressed the light ray is inactive. When the division key is depressed the mirror 121 serves to reflect the light ray to an obliquely disposed mirror 122 (Figures 2 and which is so disposed as to project the light ray toward the aligned numeral wheel 27 of the accumulator and specifically toward the drive gear 123 of the numeral wheel through an aperture 124 in the control gate 126 for the plus-minus gears 127 which serve to drive the numeral wheel through the gear 123 in a conventional manner. Numeral wheel 27 is provided with a mirror disposed on the lower face of gear 123 and this mirror is so related to the numeral wheel as to reflect the light beams from the mirror 122 when the numeral wheel 27 in the desired ordinal controlling position for an overdraft in division operation passes from 0 to 9. When the mirror 128 is in operative position the light ray is reflected downwardly again through the aperture 124 to a second obliquely disposed mirror 129 which is so related to the mirror 128 and the mirror 67 as to direct the light beams into the lowermost aperture 72 (Figure 3) so that the light sensitive device 55 will be energized and through the amplifier 86 operate solenoid 132. The solenoid 132 is operatively connected by means similar to the mechanism shown in Figure 12 to the program control shaft of the division control mechanism which corresponds to the shaft 222 shown in the patent 2,327,981 so that the program control shaft will be shifted axially to initiate correction of the overdraft, shifting of the carriage, and resetting of the machine for subtraction in the next adjacent order.

If desired the functions performed mechanically by the program control shaft in the above noted Patent No. 2,327,981 could also be utilized to control similar opera- 6 tions in an optical-electrical manner as disclosed therein by causing the control shaft 222 to appropriately position light ray ofisetting mirrors of the character disclosed herein with respect to the paths of appropriate light rays to energize solenoids and condition the machine for addition, shifting and subtraction during the division operation. In this connection the shift controlling light rays can be employed in conjunction with a half-silvered mirror similar to the mirror 62a which would provide a portion of the shift control light ray of the desired direction for use in automatic division control. Similarly if desired the plus and minus functions of the keys 34 and 35 could also be exercised in a similar manner by providing additional light rays and an optical-electrical control system for shifting the plus-minus control gate 126.

In general the various operations controlling optical means described above are similar to those described in our patent above referred to, in that an individual light ray is provided for each machine operation which is to be controlled and is directed past the various control keys which are related to the desired function and are adapted to energize a light responsive device to effect the machine control. As noted, the above description is in accordance with our above identified patent except for the description of the means for modulating the various light beams, and the common photocell for receiving these light beams.

In accordance with instant invention the sources of light are modulated and a common electrical circuit is provided to generate frequencies corresponding to the periodicity of the various light rays and this common circuit includes tuned magnetic clutches or solenoids each of which is responsive to the particular frequency corresponding to the function which it controls. A single light responsive device 55 is shown in the common circuit, however, a plurality of such devices may be employed as shown in our said patent.

In Figure 3 is illustrated a light sensitive cell amplifier 86 for energizing and controlling a plurality of tuned solenoid clutches 87, 93, 107, 108 and 132. A light sensitive device 55 which may be of an elongated shape as shown or may consist of a plurality of light sensitive cells as hereinafter described is connected to the input of the amplifier tube 86, and is employed for receiving the light beams transmitted through the apertures 56, 57, 58, 59 and 60 of the compartment 52, reflected by the various mirror systems as herein described and passed through the apertures 68, 69, 70, 71 and 72 of the compartment 54. Inside of the compartment 52 is provided a rotary shutter 51a attached to the motor shaft 141 and having a perforated cylindrical section which is rotated past the elongated lamp 53 so that a plurality of periodically interrupted light beams each having a different periodicity are emitted from the aperture systems 56, 57, 58, 59 and 60 as the rotary shutter 51a is rotated. The apertures are formed in bands around the cylindrical surface of the shutter device 51a, and each band of apertures includes a different number of apertures so that the aperture band 156, for example, sends a different number of light impulses to the light sensitive cell 55 during each rotation of the shutter 51a from the number of light impulses sent by the aperture band 157, by the aperture band 158, the aperture band 159, and the aperture band 160.

The light source 53 (Figure 3) is preferably energized by direct current from the output of the rectifier apparatus 170 so that a substantially continuous light is produced by the source 53, and this light is broken up into pulsed or modulated beams, each of these light beams being pulsed or modulated differently, depending upon the aperture bands 156, 157, 158, 159 and 160 through which they are passed. As a result, the output of the light sensitive device 55 consists of pulsating currents of different frequencies fed to the input of the amplifier 86 through the resistor capacitor network consisting of capacitors 171, 172 and resistors 173 and 174, and these difierent frequencies are amplified by the amplifier 86 which may be a triode or a tetrode, or a pentode, or a series or cascade of amplifier tubes, as desired. The output of the amplifier 86 is impressed upon the tuned solenoids 87, 93, 107, 108 and 132 to control or initiate the mechanisms associated therewith.

These solenoids 87, 93, 107, 108 and 132 are tuned to different frequencies by capacitors 87a, 93a, 107a, 108a and 132a, respectively, so that solenoid 87 is tuned to the frequency corresponding to that produced by the light emitted from the aperture bank 156 of the shutter device 51a, solenoid 107 is tuned to the frequency of aperture band 157, solenoid 108 to aperture band 158, solenoid 93 to the frequency of aperture band 159 and solenoid 132 is tuned to the frequency of aperture band 160. This tuning is accomplished by connecting small capacitors in series with the windings of the solenoids as mentioned above soas to bring the inductance of these windings into series resonance with respective frequencies; however,

it may be accomplished by the distributed capacity of the windings themselves and the inductances of the windings as well as the distributed capacities thereof and the magnetic properties of the cores thereof may be made of different values so as to tune each solenoid to a different frequency.

The lamp 53 positioned within the rotary shutter 51a is supported by a stationary member 175 which is preferably of insulation material and carries conventional electrical connectors that are connected to the lamp and to the wires 178-179 for energizing the lamp from the output filter circuit of the rectifier apparatus 170.

The lower end of the rotary shutter 51a may be provided with a ball or similar bearing arrangement 180 about the member 175 for stabilizing the rotation of the shutter 51a and to make the apparatus more rugged.

The rectifier apparatus 170 consists of a conventional arrangement including a transformer 181 having a primary winding 182 adapted to be connected to a 110 volt A. C. circuit or similar circuit, a center tapped secondary winding 183 for supplying the plate current to the amplifier 86 and voltage to the light sensitive device 55, and filament windings 184 and 185 for the amplifier 86 and rectifier 186. The extremities of the winding 183 are connected to the anodes of rectifier 186 and the center tap of this winding is connected to one side of the filter capacitor 187, the other side of this capacitor being connected to the rectifier filament winding 185. Capacitors 187, 189, 191 and 172, choke coil 188 and resistor 190 comprise the filter network. Suitable taps and connections are provided to the voltage dividing resistor 190 so that the plate current and screen grid potential and control grid bias for the amplifier 86, potential for the light sensitive device 55 and current for the lamp 53 may be derived from the same rectifier apparatus. If necessary a suitable ballast resistor may be connected in series with the lamp 53 where this lamp is of a conventional fluorescent type.

While certain preferred embodiments have been shown and described it is apparent that the invention is capable of further variation and modification within the scope of the claims appended hereto.

We claim:

1. In an electro-optical calculating machine the combination of a source of light, means for deriving a plurality of beams of light from said source, means for modulating each of said light beams in accordance with a different frequency, key operated means for selectively controlling the transmission of said beams, a light responsive device for receiving said light beams, an amplifymg device connected to said light responsive device, a plurality of electro-magnetic clutches for controlling machine operation and respectively corresponding to said beams of light, and means connected to said amplifier device for selectively controlling each of said respective magnetic clutches in response to the associated light beam.

2. In an electro-optical calculating machine, means for simultaneously producing a plurality of beams of hght modulated in accordance with different frequencies, key operated means for controlling said beams, a light responsive device for receiving said light beams, an amplifying device connected to said light responsive device, a plurality of electro-magnetic clutches for controlling machine operation and respectively corresponding to said beams of light, and means connected to said amplifier device for selectively controlling each of said respective magnetic clutches in response to the associated light beam.

3. In an electro-optical calculating machine, the combination of a source of light, means for simultaneously deriving a plurality of beams of light from said source, means for characterizing each of said beams, key operated means for controlling said beams in accordance with operations to be performed, a light responsive device for receiving said light beams, a plurality of electro-magnetic clutches corresponding respectively to said plurality of light beams, and means connected to said light responsive device for selectively controlling said magnetic clutches in response to the characteristic of the corresponding light beam.

4. In a calculating machine, the combination of a source of radiant energy, means for simultaneously deriving a plurality of beams of radiant energy from said source, means for characterizing each of said beams, key operated means for selectively controlling said beams in accordance with operations to be performed, a device responsive to said radiant energy for receiving said beams, a plurality of electromagnetic clutches, and means connected to said last mentioned device for selectively controlling said magnetic clutches in accordance with the respective characteristics of said beams.

5. In a calculating machine having a plurality of operation control devices and a corresponding plurality of operation control keys, means providing a plurality of modulated light rays associated respectively with said keys for controlled transmission thereby, an enabling means for each of said operation control devices tuned to the modulation of one of said light rays, and a common electrical circuit responsive to said light rays and connected to said enabling means.

6. In a calculating machine having a plurality of electrical operation control devices tuned for response to a given frequency and a corresponding plurality of operation control keys, means providing a plurality of modulated light rays associated respectively with said keys for controlled transmission thereby, and a common electrical circuit responsive to said light rays and connected to control said devices.

7. In a calculating machine having a plurality of operation control devices and a corresponding plurality of of operation control keys, means providing a plurality of modulated light rays associated respectively with said keys, means associated with said keys for controlling the transmission of different ones of said light rays, means responsive to said light rays on transmission thereof for producing electric currents of different frequencies corresponding to the modulation of said light rays respectively, and control clutches for said operation control devices connected to be controlled by said currents of different frequencies and having means selectively responsive to said currents of different frequencies.

8. In an electro-optical calculating machine, means for producing a plurality of beams of light, means for modulating each of said beams in accordance with a different frequency, key operated means for selectively controlling transmission of said beams, a light responsive device for receiving said light beams and amplifying device connected to said light responsive device, a plurality of electromagnetic clutches for controlling machine opera- U011, means responsive to said light beams for producing electric current corresponding to the frequencies with which said light beams are modulated and devices tuned respectively to the frequencies of said currents connected to said amplifying devices and to said clutches for selectively controlling the energization of said clutches.

9. In a calculating machine having a body and calculating mechanism therein, a keyboard having a pattern of operating control keys for said calculating mechanism, means housed within the body for producing a plurality of beams of light and for modulating each of said beams in accordance with a different frequency, optical means for directing said light beams past a plurality of said keys for controlled transmission of the light beams by the keys, a light responsive device for receiving said light beams upon transmission thereof, and a plurality of electromagnetic clutches for selectively controlling operation of said calculating mechanism and including devices tuned respectively to the current frequencies produced by said beams of light.

10. In a calculating machine having plurality of operation control devices and a plurality of operation control keys, means providing a plurality of modulated light rays for controlling transmission by said keys, at least one of said keys serving to simultaneously cause transmission of a plurality of said light rays, and a common electrical circuit selectively responsive to said light rays and conv nected to control said devices selectively in accordance with the transmitted rays 11. In an electro-optical calculating machine, means for producing simultaneously a plurality of beams of light modulated in accordance with different frequencies, key operated means for controlling the transmission simultaneously of a plurality of said beams, a light sensitive device for receiving said light beams, an amplifying device connected to said light sensitive device, a plurality of electromagnetic clutches for controlling machine operation and respectively correspondingto said beams of light, and means connected to said amplifier device for selectively controlling each of said respective magnetic clutches in response to the associated light beam.

References Cited in the file of this patent UNITED STATES PATENTS 1,975,486 Thomas Oct. 2, 1934 1,998,461 Kucher Apr. 23, 1935 2,234,832 Potts Mar. 11, 1941 2,295,000 Morse Sept. 8, 1942 2,355,281 Dickinson Aug. 8, 1944 2,571,141 Knoblaugh et al Oct. 16, 1951 

